blackman



3 Sheets-Sheet 1.

(No Model.)

H. BLACKMAN. APPARATUS PoE DISINTEGEATING PIBEES AND EECOVEEING n SUEPUEOUS GASES EMPLOYED TEEEEIN.

Patented Dec. 11, 1894.

ASSE ESQ A: u..

WITNESSESI 75. @7W

Tn: mams Firms un., Puoraumo., WASHINGTON. D, cA

(No Model.)A 3 Sheets-Sheet 2.

H. BLAGKMAN.

APPARATUS POR DISINTEGRATING PIBERS AND REGOVERING SULPUROUS GASES EMPLOYED THEREIN.

Patented Dec. 11, 1894.

VENTOR;

(No Model.) '3 Sheets-Sheet 3.

H. BLAGKMAN.- APPARATUS POR DISINTEG-RATING PIBERS AND REGOVERJING SULPUROUS GASES EMPLOYED THEREIN.

No. 530,634. Patented Dec. 11, 1894.

Ffa-:3.

INYENTOR;

72( By his Affomeys,

l preferably of a sulphite of soda, potash, lime,

, of the acid solution.

UNITED STATES PATENT OFFICE,

HENRY BLACKMAN, or NEW YORK, N. Y.

APPARATUS FOR DISINTEGRATING FIBERS AND yRECOVERING SULFUROUS GASES EMPLOYED THEREIN.

SPECIFICATION forming part of Letters Patent N o. 530,634dated December 11, 1894.

Original application led October 21, 1889, Serial To @ZZ whom it may concern,.-

Be it 'known that I, HENRY BLACKMAN, a citizen of the United States, residing in New York city, York, have invented certain new and useful Improvements in Apparatus for Disintegrating Fibers and Recovering Sulfurous Gases Employed Therein, of which the following is a specification.

This application is a division of my' application for patent for process and apparatus for making paper pulp, tiled October 21, 1889, Serial No. 327,615.

This invention relates to what is known as the sulphurous or sulphite process of disintegrating fibers for the manufacture of paper pulp. It involves in part the use of what is known as the vacuunfprocess of disintegrating fibers, described and claimed in my Patent No. 369,836, dated September 13, 1887.

According to what is known as the sulphurous or sulphite process of making paper pulp, the wood, straw, or other fibrous matter is exposed in a digester under considerable pressure and at a high temperature, to the action of a solution of sulphurous acid, or

or other alkali or base. The boiling is con'l tinued for several hours, during which time by the action of the sulphurous or sulphite solution, the gummy or resinous matters, or other cementing substances that bind the bers together, are decomposed or dissolved, thereby freeing the pure cellulose which constitutes the essential portion of the fibers, so that at the conclusion of the .digesting operation the fibrous matter is discharged as anl impure pulp requiring only washing and beating to tit it t'or use. The digester employed usually consists of a steel shell of great strength to withstand the heavy pressure, and lined with lead to resist the corrosive action The solution usually and preferably employed consists of a monosulphite or'bisulphite of lime with an excess of sulphurous acid. This solution is prepared in various ways, one method vbeing to introduce lime Water into the .'digester and then No. 327,615. Divided and this 354,760.` (Nomodel.)

in the county and State of New i force sulphurous acid gas into the digester while agitating its contents, so that thesoluappnationried June 9, 1890. serial Nt orl containing trays of lim`e,water being caused to trickle down through thelimeorlimestone, While sulphurous acid gas is admitted at the bottom of the tower from a retort in which sulphur is burned, or in which pyrites are roasted. The ascending gas combines with the descendinglime-impregnated Water, forminga solution of sulphitejrof lime which is carried 0E from thev bottom of the tower and is eventually pumped into the digester. In this process it has usually been necessary or advisable to force an additional proportion of gas into the digester.

The acid or sulphite process of disintegrating bers is subject to'certain disadvantages,

among which may be mentioned the'frequent discoloration of the ber, due it is believed, to the presence of a residue of sulphur gases in the pulp, which upon its exposure to the atmosphere gives rise to chemical reactions by which the color of the pulp is impaired.

The sulphur gases also escape into the atmosphereupon the discharge of the pulp from the digesters, thereby giving rise to intensely disagreeable odors about the mill and constituting it av nuisance to the; neighborhood. The discharge of the spent liquors into streams or lrivers results in poisoning their waters and gives rise to unhealthy odors. The prevention of thesev .diiculties, as well as the attainment of a greater economy in the working of the sulphite process, is animportant object of my present invention.

In accordance with my present invention I provide one or more d'igesters such as are used in the well known sulphite'process,and a vacuum chamber or tank to which the digester is connected so that its contents may be'blown oi into the vacuum chamber, which has a capacity sufficient to receive the entire charge from one digesten Since this vacuum chamber is normally closed at itsbottom and is so constructed as to retain the entire charge of fibrous material discharged into itfrom the digester,"which retaining feature isv one of its herein characteristic and important features, it may be appropriately designated a vacnum retaining chamber and this designation is hereinafter adopted. I also provide a pump for maintaining a vacuum in this chamber, and between the pump and vacuum retaining chamber I provide a vapor separator and condenser. I also provide a closed tank having agitating devices called the sulphite mixer, and another closed tank, preferably with agitating devices, called the recovery tank. These several tanks or vessels are connected together through suitable pipes suitably provided with valves for regulating the iow of gases or liquids therethrough and connected with pumps for circulating the gases or liquids.

In using this apparatus I proceed preferably as follows:-'l`he chipped wood or other described in my aforesaid patent.

fibrous matter is digestedin the usual or any suitable way in a solution of sulphite or bisulphite of lime or other base, in a suitable digester, and under the necessary heat and pressure. At the end of the period of digestion, and preferably also one or more times during the digesting, the fibrous matter is disrupted by being blown off from the digester into a vacuum, in accordance with my vacuum process of disintegration This disruption is accomplished by blowing oft the fibrous matter and liquor from the digester into the vacuum retaining chamber under a considerable pressure in the digester, and at a high temperature, while in the vacuum retaining chamber a vacuum or rarefaction is maintained by the operation of the vacuum pump. The fibrous matter enters the vacuum retaining chamber through a contracted nozzle or orifice, on escaping from which into the vacuum the liquid in the cells of the fibrous matter being suddenly relieved of pressure is vaporized or converted into steam which tears the fibers asunder, or disrupts them. The steam,vapor and solvent gas pass out at the top of the vacuum retaining chamber and are carried through the condenser in which the steam is condensed and passed thence to the pump. The fibrous matter falls to the bottom of the vacuum retaining chamber together with the portion of the liquor which is notvaporized. During the blowing off the disengaged gas is pumped from the vacuum pump back into the top of the digester to assist in maintaining the pressure therein. At each. intermediate blowing off, when the entire contents of the digester have been blown o into the vacuum retaining chamber they are returned again to the digester either by pumping them back or by opening valves and turning a pressure of steam into the vacuum retaining chamber sufficient to y force them to ow through the communicating pipe from the vacuumretaining chamber into the digester. This return or transfer of the brous matter and liquor may be assisted by forming a vacuum in the digester by connecting it with the vacuum pump. This disruption of the fibrous matter by blowing it off into the vacuum retaining chamber and the subsequent return of the fibrous matter to the digester should be practiced several times during the period of digestion. At one of the disruptive operations, and preferably after the digestion 4has been continued about eight orten hours, the liquor or sulphite solution should be changed. At this time the gases drawn from the vacuum retaining chamber during the blowing off are forced from the vacuum pump into the sulphite mixer, where they are utilized for the production or enrichment of the sulphite solution therein. The fibrous matter having all been discharged into the vacuum retaining chamber, the pressure in the latter is restored to that of the atmosphere, or to above atmospheric pressure, andthe spent liquor is drained off from the fibrous matter, being carried into the recovery tank. Fresh liquor or sulphite solution is then introduced into the vacuum retaining chamber, and the fibrous matter and fresh liquor are pumpedor blown back from the vacuum retaining chamber into the digester, whereupon the digesting process is resumed. When the digestion is completed the pulp is subjected to a final disruptive blowing oft into the vacuum retaining chamber. During this blowing ott it is preferable to pump the p ulp and liquor back from the vacuum retaining chamber into the digester as fast as it enters, so that it may again be blown out and kept in circulation until it has been blown through the contracted nozzle into `the vacuum retaining chamber as many times as may be desired to complete the separation of the fibers. When the entire mass has thus been circulated two or more times, the pulp outlet from the vacuum retaining chamber is closed and all the pulp from the digester is blown into the vacuum retaining chamber. During the entire final blowing olf the sulphur-ous gas is pumped into the sulphite mixer where it is utilized for the production or enrichment of the sulphite solution therein. When the entire charge of pulp has been accumulated in the vacuum retaining chamber the vacuum is discontinued and the spent liquor is drained olif from the pulp into the recovery tank. The pulp is then still irnpregnated to a considerable extent with sulphurous acid gas, for the removal of which the pulp is heated while under vacuum. This is accomplished by injecting steam into the bottom of the vacuum retaining chamber so that it passes upward through the mass of pulp, the gas thus liberated and the steam being drawn off by the vacuum. Thus nearly everytrace of sulphurous gas is eliminated from the pulp. Hot water is then introduced into the top of the vacuum retainingv chamber and the accumulated pulp is washed out to the pump which pumps it to the usual wash tanks where it is washed in the usual manner and is run into the usual clean pulp chest. It may then be used in any known tator in Ithe mixer.

way for paper manufacture. In the sulphite mixer the sulphitey solution is prepared. The sulphurous gases thus drawn'out by the vacuum pump during the different stages of Vthe operation whenever they are not forced back into the digester are forced into' this sulphite mixer. 'Lime waterl is also introduced to the mixer in suitable proportions and the gas and liquor are thoroughly commingled by the action of the revolving agi In case a jet condenser is used forcondensing the steam or vapor drawn from the vacuum retaining chamber, it is preferably supplied with cold lime Water which combines with some of the sulphurous gas and which is theny pumped into the sulphite mixer. Additional lime water-is introduced directly intothe mixer whenever nec'- 'essary In the recovery tank the spent liquor is heated under vacuum and the sulphurous gas thus driven oft isr pumped to the sulphite` mixer. This heating ot the liquor is preferably accomplished by injecting steam into it at the bottom of the tank. The remaining liquor may then be treated for therecovery of its tannic acid and other valuable constituents, after which the residue of liquor will be run oft tothe sewer.

The present improved apparatus is illustrated in the accompanying drawings, where- 111-,

Figure l is a general view of the apparatus on a small scale chieiy in elevation,but partly in vertical section. Fig. 2 is a vertical section on a larger scale of the digester, vacuum retaining chamber, condenser, and their oommunicating pipes. Fig. 3 is a vertical section on the same scale as Fig. 2, of a tank having an agitator within it, which may be either the sulphite mixer or the recovery tank. Fig. 4 is a horizontal section of part of Fig. 1, cut on the plane of the line 4-4 therein.

Referring to the drawings, A designates the digester; B, the vacuum retaining chamber; C, the condenser; D, the vacuum pump; E, the sulphite mixer; F, the recovery tank; G, one of the wash-tanks and H th'e boilingr tank.

I, J, K and L are pumps which may be centrifugal pumps.

The digester A may be of any known construction, such, tor example, as either of those shown in my Patents Nos. 369,836 and 369,834c of September 13, 1887. In the construction shown it consists of a steel outer shell with an inner lining of lead, as is common in working under the acid or sulphite processes, with a large opening a at its top through which to introduce the fibrous matter, and an outlet a. at its bottom from` which leads a pipe b connecting with a pipe b extending to the vac-v uum retaining chamber B, and there terminating in Va contracted nozzle or discharge orifice c. In the bottom of the digester is fitted a conical screen or false bottom a2 in the space beneath which is preferably a steamcoil or jacket d, the admission of steam to which from the steam-pipe S is'controlled by a valve 5. From the space beneath the screen a2, a pipe e leads to the pump I, and a pipe e leads from this pump to the upper part of the digester, which it enters. Thus by operating this pump the liquor may be drawn down through the mass of fiber Which-rests on the screen azand returned into the top of the digester, thus instituting a circulation of the liquor through the fibrous matter. The ontlet a is closed by a valve 6 in the discharge pipe b. Steam from the pipe S is admitted into the top ofthe digester through a valve 7.

If the tank His not used the inlet opening a at the top of the digester is closed by a manhole plate, as shown in Fig. 2. When the tank H- is employed, however, it is arranged preferably directly over the digester and communicates therewith through an outlet-pipe fentering the opening a and closed by a valve 8. The tank H has a perforated` screen or false bottom f in the space beneath which is a steam coil f2 into which steam is admitted through the valve 9 in order to supply heat for boiling the fibrous matter in the tank.

The vacuum retaining chamber B is the same in its disruptive principle of operation as the vacuum retaining chambers shown in my said Patents Nos. 369,836 and 369,834. Instead, however, of being a comparatively shallow box or chamber partially divided by a pendent partition or target and with an always open outlet at Athe bottom, it is constructed as a large npr-ightvessel, preferably cylindrical, normally closed'at its bottom and having a capacity sufficient to receive and maintain in its lower portion the' entire contents of the digester A. The nozzle c enters it at gne side near its top and directs the stream of fibrous matter against the target g, which is arranged to project down from the IOO top of the chamber. This target has the same tank G, into which it discharges, being governed by a valve 12.

From the top of the vacuum retaining chamber B a vapor-pipe t' extends upwardly, being provided with a-valve 13, and enters a vapor separator C which consists of a box or chamber having a pendent target or partition t" inl its upper part to dedect downwardly the stream of vapors owing through the chamberl on their way to the outlet-pipe a2. This outlet pipe leads into the top of the condenser C, which may be of any construction common for condensers, and either a surface or a jet condenser. The condenser shown iis a /jet condenser, receiving cold water, preferably IIO 3o Fig. 2.

65 ing governed by a valve, 24..

ro sisting chiefly of sulphurous gas and steam,

flow out of the side of a pipe 7c which leads down and communicates through the tWo-Way valve 14 with the suctioirpipe 7c of the vacuum pump D. The uncondensed steam or va- 15 por is condensed in this pipe 7a by cold Water showered thereinto from a perforated pipe k2,

fed by a branch from the the pipe W and controlled by a valve lo'. The vapor which is separated in the chamber C Hows down a zo pipe i3, and is discharged either through a pipe t4 into the condenser 0,01- through a pipe i5 back into the vacuum retaining chamber B, its iioW being determined by a two-way cock 17.

The vacuum in the cha'mber B is maintained by the operation of the pump D, which draws the gases or vapors out through the pipe t', separator C', condenser C, and pipe la, the valve 14 being in the position shown in In order that the same pump may also serve for drawing the sulphur gas from the top of the digester A, a pipe Z is provided leading from the top of the digesterand com municating with the pump, preferably by joining the pipe vl above its valve 13, so that by closing this valve and opening a valve 18 in the pipe Z the gases or vapors may be drawn through this pipe and through the separator C', condenser C and pipe 7a to the pump. The

4o gases drawn ol by the pump are discharged through a pipe m in either of three different directions, namely: rst, through a branch pipe m governed by a valve 19 into the sulphite mixer E; second, through a branch pipe n into a long main pipe p which extends from the pump K to a pipe p communicating with the digester or digesters, as Will be presently described, the flow through the pipe n being governed by a valve 20; third, in case a lime 5o tower is used the gas may be discharged through a branch pipe ritzigoverned by a valve 2l and leading to the tower.

The liquid which descends from the coudenser C and which Will usuallybe rich in snlphurus gas, is forced by the pump .l

6o as shown in Fig. l, with an inlet pipe W for admitting lime Water, being governed by a valve 23, and with a pipe M for admitting sulphurous gas from the retort or furnace in which this gas is produced, its admission be- In addition, the sulphite mixer is provided With an outlet pipe o governed by a valve 25, and leading to the pump K, by which the sulphiteliquor or solution prepared in the mixer E is discharged into the digester, or Wherever else it is required.

The sulphite mixer, which is a closed tank of considerable strength, is provided preterably with agitating devices, as shown in Fig. 3. In this preferred construction the agitator consistsof a vertical shaft t carryinglateral arms if to which are fixed stirring-ar1ns or cross-pieces t2 t2, which as they revolve alternate with fixed arms ist?, mounted on a crosebar t4, which is supported from the Walls of the tank. The shaftt is stepped in a cupbearing at its lower end, and passed out through the stuffing-box in the top of the tank, its upper end being driven by any snitable gearing.

The liquor from the sulphite mixer is pumped by the pump K through the pipe p, and either through the pipe q Which enters the upper part of the vacuum retaining chamber B, the flow into this pipe being governed by a two-way valve 26, or it is pumped through the entire length of the pipep into the pipe p and thence into the digester either through a pipe/r` ora pipe s. The pipe fr enters the bottom of the dgester beneath the screen a2, and is controlled by a valve 27. "lhepipesextends to the top of the digester, the flow through it being controlled by a valve 28. The pipe p is furnished with a valve 29 between the pump K and branch pipe n in order to prevent any back flow from the pump D through the pipes fn andp toward the pump K. Varm or hot water is supplied by a pipe W2, which has two branches, one leading to the boiling tank ll and controlled by a valve 30, and the other leading to the top of the vacun m retaining chamber B and controlled by a valve l.

The steam pipe S in addition to branches communicating through the valves 9 and 5 with the tank H and digester A respectively, has also a branch pipe s' leading to the top of the vacuum retaining chamber B, and controlled by a valve 32, a branch s2 leading to the bottom of the vacuum retaining chamber beneath the screen g' therein and controlled by a valve 33 and a branch s3 leading to the outlet a from the digester and controlled by a valve St.

The recovery tank F is a closed vessel of suitable strength and lined with lead to resist corrosion, and preferably tted with the same agitating devices as the sulphite mixer E, as shownin Fig. 'lhe spent liquor from which the sulphur gas is to be recovered is discharged into this tank through a pipe u leading from the bottom of the vacu um retaining chamber B beneath the screen g and entering the recovery tank, preferably at the bottom. Itis controlled by a valve 35. From the top ofthe tank F a pipe n extends to the three-way valve le by which it may be put into connection With the suction-pipe 7c of the vacuum pump in order that this pump may draw the sulphur-ous gas from the tank F.

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The liquor is heated by steam admitted through a pipe S controlled by a valvie 36, either by admitting the steam directly into the liquor, or'bythe use of a steam-coil or jacket. After the sulphurous gas has been recovered by the action of the heat and vacuum, the liquor may be treatedfor therecovery of tannic acid or any other valuable constituents that it may contain, or it may be treated to deodorize or otherwise purify it. For this ,purpose any chemical-agents may be introduced through a funnel inlet of any usual construction. Finally the spent liquor is discharged through the pipe w leading to the sewer or elsewhere, and governed by valve 37.

The pump D may draw the sulphurous gas' either through the vpipe k, or from the tank F through the pipe o, or from the retort in' which thisgas `is generated through a pipe M, f

which latter pipe communicates with itssuction chamber, being controlled by a valve 38.-

The wash-tank G is of a-ny usual construction, and requires no description.

Preferably two or. more digesters A are em ploy'ed, since with a single digester the vacuum retaining chamber B, pump D,recovery tank F, &c., would be idle the greaterpart of the time.

In Fig. 4 I havev shown in horizontal sec-1 tion a battery of three digesters, AA A, allA connected to the one vacuum re'tainingcham-A ber B. The outlet pipes b of the three -digesters all communicate with a. single cross-v pipe b2, through which they are put into connection with the pipe b which extends up to the nozzle c. The single discharge pipe from the pump L enter's a transverse pipe h', from which three vertical lpipes h2 ascendand lead to the respective digesters. Thesingle pipe p communicates with a transverse pipe p extending under the three digesters, and from which three vertical 'pipes 'r/r ascend and enter the bottoms of the digesters, while-three pipes s sfbranch laterally from the pipe p and extend to the tops of the respective digesters.

The several valves numbered from 5 to 3Sv may be of any suitable constructions, some of these being gate-valves, others being globevalves, and others being two-way cocks.

The general operation of the apparatus will l be well understood from the description which I have given of the mode of operation. I will, however, describe some of the .operations of the apparatus which may not be apparent from such description. After the 'fibrous matter has beeuplaced .in the digester, the solution or liquor is introduced into the ,digester from the'sulphite mixer by the pump K, owing through thepipes o p, and either 'r or s, according as itis desired to introduce it at the bottom or`at the top of the digester.

v It will usually be introduced at the top, in

which case the valves 25,' 29 and 28 will be opened. In order to blow 0E the fibrous matter into the vacuum retaining chamber to disrupt it, the valve 13 is opened, the two-way cock `14` is s etto the position shown, and the pumpk D is started and operated until a sufticient vacuum is produced in the chamber` B." A sufficient pressure being maintained in the digester A, the valve 6 is opened, whereuponl by reason of the pressure behind it, andthe suction infadvance,lthe fibrous mass isforced out and flows i-n a continuous stream through` the nozzle c into the vacuumchaml and 11 and operating the pump L, whereby the fibrous matter will be circulated between the digester and vacuumchamber until it has passed through the nozzle as many times as may bedesired or the fibrous matter may, by keeping the valve l0 closed, be permit-ted toaccumulate in the vaeu umretaining cha-mber. A t each intermediate blowing o or disruptive operation, the sul ph urous gases in the vacuum retaining chamber are pumped back from the pump D into the digester A through the pipes m n p and s. Whenever in the course of a digesting operation itpis found necessary to introduce additional sulphurous gas into the digester, this is done by the pump D which-draws the gas eitherfrom the pipe M or from the recovery tank F through the pipe/v and pumps it through pipes m np and (preferably) fr into the bottom of the digester. To change thel liquor after any blow- )ing off of the pulp thevalve 10 is kept closed,

and when all the pulp has been blown into chamber, valve 13 is closed and steam is admitted at 32 to till the vacuum and generate ay steam ypressure in the chamber B, whereupon the valve 35 is opened and the liquor is forcedorruns out through the pipe u into the recovery tank. Fresh liquor is then su pplied from the sulphite mixer through pipe o,` pump K, pipe p, cock 26 and pipe q. At the final blowingoff of the pulp into the vacuum retaining chamber the spent liquor is drawn o' in the same manner, vand the sulphurous gas is then driven olf from the pulp by` admitting steam ythrough valve 33,.so that it ascends through the mass of pulp, while at the same time the valve 13 being opened the pump D is operated toldraw od the sulphurous gas thus expelled. When the sulphurous gas has thus been sufficiently eliminated, valves 13 and 33 are closed and valves 10 and 31are opened, so that water entersthe vacuum retaining chamber and the pulp is washed down into the pump L which forces it through pipes h and 71,3 into one of the wash-tanks G.

The agitator in the sulphite mixer E need be revolved only at the times when gas is being pumped into it by the pump D, or injected from the pipe M.

Whenever during the digestion it is desiredl to draw 0E the sulphurous gas from the digester, this isdone by closing the valve 13 and opening the valve 18 and operating the pump D, so that the gas is dra'wn off through the pipe Z. It may be pumped into the sulphite mixer and its place supplied by fresh gas, or it may be pumped back through the pipes tm np and r into the digester.

lf that part of my invention which has reference to the sulphite mixer E be not used, its functions may be performed i-n a measure by theusual lime tower, in which case instead of liquidsand gases being pumped into the tank E, the liquids will be pumped to the top of the tower and the gases be pumped into its bottom, as is usual in the operation of such towers. The liquid drawn from the bottom of the tower will be conducted to the pump K which will distribute it through the pipes p q T and s in the manner shown. The use of the sulphite mixer is preferred, however, on account of the greater cheapness and expedition in the recovery of the sulphurous gas, and because the gas is confined so 4that it cannot escape to the atmosphere and give rise to foul odors.

It will of course be understood that equivalent devices or means may be substituted for the means shown. For example, the pumps I, J, K and L, instead of being centrifugal pumps may be any other'kind or construction of pump, or any other apparatus known to' the arts which is capable ot' substitution for a pump to accomplish the same work. For example, a monte-j us may be substituted for the pump L; or in any case where a pump is used to transfer a liquid from one closed vessel to another, the pump may be omitted entirely and the transfer be effected by establishing a difference of pressures between the two vessels, the one from which the liquid is being expelled being given an internal pressure sufficiently greater than that in the vessel to which the liquid is being introduced, to overcome the friction and other resistance opposing the ow of the liquid; or the respective vessels may be arranged at different,

levels so that the liquid will iiow from the higher to the lower vessel upon the establishment of an equilibrium of internal press- The latter arrangement is shown in connection with the vessels B and F, the

former being shown arranged on a higher` level than the latter, so that the liquid runs oii itself whenever the valve 35 is open and the pressures in the two vessels are the same or nearly so. If the tank F, however, were arranged on the same level as the chamber B, or at a higher level, it would be necessary to introduce a pump into the pipe u, asin the case of the pumps K and L.

All of the modifications of apparatus and their connections together shown in my said Patents Nos. 369,834 and 369,836, in so far as the same are applicable in connection with my present invention, are to be construed as though their illustration and description were repeated in my present application. For example, the substitution for the vacuum pump D as the means for maintaining the vacuum in the vacuum retaining chamber, of an ejector, may be made and will serve `'some of the purposes of my present invention.

-In mysaid application, Serial No. 327,615, of which the present application is a division, whereinA is described the herein-described process of digesting and disrupting, there is y.

claimed the process of preparing paper pulp consistingV in partially digesting the vfibers,

then disrupting the bers by blowing them into the vacuum, and then resuming the digestion, and repeating the blowing into a vacuum until the fibers are reduced to the desired fineness. There isalso therein claimed so much of the herein described apparatus as is `necessary for carrying out the process claimed in said application; that is to say, there is claimed thedigester, the vacuum chamber, the vacuum pump, and the connections between the same which enable the fibers, solution and gases to be transferred back and forth between said digester and vacuum chamber. All of the matter claimed in said application I herein disclaim.

I claim as my invention the several improvements in the disintegration of brous matter for the manufacture of paper-pulp and in apparatus therefor, defined as follows, each substantially as hereinbefore specified, namely: y

l. The combination of the digester, the vacuum retaining chamber connected therewith into which the contents of said digester are discharged and retained, the vacuum pump connected on its suction side with the upper part of said vacuum retaining chamber, and a recovering conduit leading from the discharge side of said pump, substantially as set forth, whereby the fibrous material when discharged from said digester into said vacuum retaining chamber is disrupted and retained in said chamber, and the disengaged gases are drawn off by said pump and discharged into said recovering conduit .for further utilization.

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2. The digester, the vacuum retaining4 chamber connected therewith into which the contents of said digester are discharged and retained, the vacuum pump connected on its suction side with the upper part of said vacuum retaining chamber, and a recovering conduit leading from the discharge side of said pump, in combination with a spent liquid draining pipe leading from the bottom of said vacuum retaining chamber, a valve therefor, a steam-introducing pipe opening into the bottom of said vacuum'retaining chamber, and `a valve therefor, substantially as set forth, whereby the steam is forced through the drained pulp and the gases are drawn off therefrom by the vacuum pump while the pulp is within the vacuum retaining chamber.

3. VThe digester, the vacuum retaining chamber connected therewith intowhich the contents of said digester are discharged and retained, the vacuum pump connected on its suction side with the upper part of said vacuum retaining chamber', and a'recoveringeonduit leading from theI discharge. side of said pump, in combination with a Spentliq'uid re-` covery tank, a pipe leading from the bottom of said vacuum retaining chamber to said re- 4covery tank, a valve in said pipe, means` forf heating the contents ot' said recovery tank,

and arpipe leading from 'the upper part of said recovery tank to a vacuum pump, sub# 1o stantially as set forth, whereby the digesting v gas is recovered from the Spent liquid drawn 0E from the vacuum retaining chamber.

In witness whereof I have hereunto signed my name in the presence of two subseribing ARTHUR O. FRASER, l JNO. E. GAvIN. 

